Immune-Evasive and Highly Transmissible New Variant... "Reinfections Expected to Increase if Introduced Domestically"

Omicron Subvariant BA.2.12.1 Drives Resurgence in the US
South Africa Faces BA.4 and BA.5 Variants... Potential Immune Evasion
"Introduction of Variants Evading Existing Immunity May Increase Reinfections"

[Image source=Yonhap News]

[Asia Economy Reporter Kim Young-won] Omicron subvariants, identified as having high transmissibility or immune evasion capabilities, have been detected both domestically and internationally. These variants are driving the resurgence of COVID-19 in countries such as the United States and South Africa, drawing attention to their potential impact in Korea.

According to health authorities on the 4th, the BA.2.12.1 variant confirmed domestically the previous day is a subvariant of BA.2, known as the "stealth Omicron." According to the New York Department of Health, BA.2.12.1 is estimated to have a detection growth rate 23-27% faster than BA.2, which itself has 30% higher transmissibility than the original Omicron.

There is also a possibility that this variant possesses immune evasion capabilities, as it has two additional amino acid mutations compared to BA.2. One of these mutations at position 452 is the same as those found in Delta and Lambda variants, which is believed to influence transmissibility and immune evasion.

As the prevalence of BA.2.12.1 increases, COVID-19 cases in the U.S. have recently been on the rise. According to the U.S. Centers for Disease Control and Prevention (CDC), BA.2.12.1 was detected in 90% of cases in central New York and surrounding areas. The 7-day average number of cases in New York rose from 3,339 on April 2 to 6,425 on April 23, nearly doubling. The share of BA.2.12.1 in the U.S. increased from 6.9% on April 2 to 28.7% on April 23.

Considering the domestic spread and variants, the CDC has reissued recommendations to mandate mask-wearing on public transportation despite court injunctions. Previously, the U.S. Transportation Security Administration (TSA) had mandated mask use on public transit following CDC guidance, but a federal court in Florida invalidated this measure on March 18.

The BA.4 and BA.5 variants spreading in South Africa have been reported to possess immune evasion properties. According to Bloomberg, South African researchers tested blood samples from individuals recovered from BA.1 against BA.4 and BA.5. In unvaccinated groups, neutralizing antibody levels dropped to one-eighth compared to BA.1, while fully vaccinated individuals showed about one-third of the neutralizing antibody levels.

With the spread of BA.4 and BA.5, COVID-19 cases and deaths in South Africa have surged. In the third week of April, new cases reached 19,291, double the previous week's 9,151. Deaths during the same period rose to 154, approximately three times the previous week's 48. As of the 3rd, the recent 7-day total cases in South Africa stood at 33,548, continuing an upward trend.

Experts predict that variants capable of immune evasion may continue to emerge. Professor Baek Soon-young, emeritus at Catholic University College of Medicine, stated, "There is a sufficient possibility that new immune-evading variants will arise," adding, "Since BA.1 and BA.2 have dominated the epidemic in Korea, if BA.4 and BA.5 are introduced later, reinfection rates could increase significantly." Professor Jung Jae-hoon of Gachon University College of Medicine's Department of Preventive Medicine forecasted at a recent forum, "Given the current high levels of natural infection and vaccination, the next variants are likely to evolve in a direction that evades immunity."

This content was produced with the assistance of AI translation services.